I once calculated it with the local rates of our supplier, which of course vary everywhere, and came to annual values of about 820 EUR for gas, 650 EUR for a mediocre air-water heat pump, and 550 EUR for a good ground-source heat pump. With gas, you inevitably get some solar included, but there are additional costs for electricity and the chimney sweep. With a heat pump, electricity costs are included in the annual performance factor. All calculated with my values (with my local prices here; with annual performance factor numbers from the Federal Heat Pump Association).
Unfortunately, a ground-source heat pump hardly pays off compared to an air-water heat pump, especially if you insulate well and, for example, like us go for KFW55. Drilling would cost us about 9,000 EUR, and the heat pumps do not differ much in price. Even with subsidies here, 4,500 EUR additional costs = 45 years. Unfortunately. I would have liked a ground-source heat pump, but the air-water heat pump is simply logical.
I would not recommend an exhaust air heat pump, that is correct. The Nibe solution with an exhaust air heat pump is also not a ventilation system. Take a look at the system. The fresh air does "NOT PASS PRE-HEATED" through holes into the house. I had such flawed solutions on my radar about a year ago as well. No no, a ventilation system is a good investment as you say, and separately there is a heating system. With a good insulation standard, the air-water heat pump is actually the best option. Ground-source heat pump if it is worth it to you (no device somewhere on the side of the house; super-best-great eco-conscience).